1. Field of the Invention
This invention relates to a mold for molding a golf ball which permits smooth ejection of the molded golf ball therefrom. The invention also relates to a golf ball formed using the mold.
2. Prior Art
Molds are conventionally used to mold golf balls. One exemplary mold is shown in FIG. 4. The mold includes separable upper and lower metallic mold halves 1 and 2 each formed with a hemi-spherical recess 3. The mold halves 1 and 2 are mated together to define a spherical cavity therebetween. Though not shown, the cavity surface is provided with a plurality of bosses for forming dimples in the surface of a golf ball. By feeding a molding material into the cavity, a golf ball 4 having a plurality of dimples in its surface is molded. The prior art mold is divided exactly at a horizontal plane corresponding to the equator 5 of the golf ball 4 into the equal mold halves 1 and 2.
This equal division gives rise to a problem when the mold halves 1 and 2 are separated at the end of molding of a golf ball. Since the golf ball surface is somewhat tacky immediately after molding, the golf ball sticks to the cavity surface. The upper and lower mold halves at their cavity surface have the same area of contact with the golf ball. Then it is uncertain whether the golf ball is caught in the upper mold half and removed from the lower mold half or caught in the lower mold half and removed from the upper mold half. This inconsistency is inconvenient for the subsequent operation of ejecting the golf ball from the mold.
The equal division is also disadvantageous in dimple distribution. Since the upper and lower mold halves are divided along the equator 5 of the golf ball 4, it is difficult to locate dimples across the equator of the golf ball. The dimple distribution must be designed such that no dimples are located on the parting line of the mold.
An object of the invention is to provide a golf ball-forming mold comprising mold segments wherein golf balls molded therein are always caught in one mold segment when the golf balls are to be ejected from the mold. Another object of the invention is to provide a golf ball which is molded using the mold so that dimples may be formed across a great circle of the ball.
The present invention provides a mold for molding a golf ball having a multiplicity of dimples in its surface by feeding a molding material into a mold cavity. The mold is composed of a plurality of, preferably two split mold segments which are mated in a separable manner to define a spherical mold cavity therein. The mold segments are split along a line off a great circle of the golf ball.
Also contemplated herein is a golf ball formed using the mold defined just above.
According to the invention, the split mold segments of the mold are split along a line off a great circle of the golf ball. When the split mold segments are mated together, the joint is off the great circle of the spherical cavity defined by the segments. When the two upper and lower mold segments are mated together, for example, the joint is off the equator of the spherical cavity defined by the segments. When the mold segments are separated for ejection, the respective mold segments at their cavity surface have different areas of contact with the golf ball. Then the golf ball as molded is caught in the mold segment of the larger contact area. That is, upon ejection, the golf ball always remains in one predetermined mold segment. Golf balls can then be always removed from the mold by a routine operation.
In producing golf balls using the mold according to the invention, since the parting line between the split mold segments is off a great circle of the spherical cavity, the parting line is not formed across the corresponding great circle of the golf ball. This permits dimples to be distributed on the great circle (the equator when the mold consists of two upper and lower mold segments) of the golf ball, contributing to the uniform distribution of dimples on the golf ball.